Two-way radio communication system



Nov. 8, 1927. 1,648,835

P. WARE TWO-WAY RADIO COMMUNICATION SYSTEM 7 Filed Sept. 4. 1920 INVENTOR ATTORNEY Patented Nov. 8, 1927.

. UNITED STATES PAUL WARE, OF NEW YORK, N. Y.,

)ASSIGNOR '10 warm RADIO, me, A oonrona'r on or DELAWARE. I

TWO-WAY RADIO COMMUNICATION SYSTEM.

Application filed September 4, 1920. Serial No. 408,132.

This invention relates to system of twoway radio communication, and has for its object to provide a system of two-way or duplex radio communication which is operable in the same manner as land wire telephone and telegraph systems, without' the necessity of changing the circuit adjustments for sending and receiving, or using throw-over switches, etc.

Previous systems of two-way communica tion have been proposed for both long and short distances, the former requiring the sending station to be at" such distance from the receiving station asto prevent the receivin circuit from being paralyzed by the powerlul sending circuit; and the latter consisting of a single transmitting and receiving element at each station, such as an audion, giving satisfactory communication over shorter distances.

The object of this invention is to provide a two-way system wherein greater distances .can be covered wherein the receiving circuit OI necessary sensitiveness will be protected from the relatively powerful transmitting circuit and both be located comparatively near each other, and in many instances on and within the same build ng, which, so far as I am aware, has not heretofore been accomplished in the case of systems involving a relatively powerful'transmitting circult separate from a sensitive receiving circuit, that is to say, one having a radiating element and the other a separate collecting element for receiving. Heretofore it has been believed that the local paralysis caused by the. relatively powerful sending circuit would render a sensitive receiving circuit in the same building inoperative, but I have discovered thatthis supposition is unfounded and am able to dispense with remote control heretofore used for medium distance. communication, and also with methods here-I tofore proposed which balance a sensitive receivingcircuit in the field of a powerfultransmitter, which requires continual readjustment and consequent reduction in operating efiiciency.

This inventionaccomplishes the following objects! (a) Provides means whereby a complete two-way, or break-in, transmitting and receiving circuit may be made to occupy no more space and require no more equipment than a one-way transmitting and receiving stat-ion capable of covering the same distance. f Y (b) Makes the improvement from a-oiieway to a two-way complete transmitting and receiving circuit without introducing any additlonal adjustments to do so.

(0) Makes the improvement from a onevway to a two-way complete transmitting and receiving circuit without reducing the customary eiticiencies of either the transmitter or recelver.

In the accompanying drawings is shown a diagrammatic representation of a system embodying a preferred form of the invention, wherein 1 Figure 1 is a general diagram, and

Figure2 is a detail diagram. -In carrying out the invention I rovide a transmitter radiating system of high capacity and low inductance, and a receiver collecting system of low capacity and high inductance, and am thereby enabled to 00- tain the best conditions for simultaneous radiation. and reception. The system as a whole is shown in Figure 1, wherein A represents a transmitting aerial mounted in the usual inanneron mast-s or towers on top of the building, and also carrying a counter poise B, the latter usually being placed below the aerial A. The aerial A and counterpoise B are wired to apparatus contained within a weatherproof box C carried by one of the masts, and the box C is connected by metal sheathed conductors F to a power unit D within the building, and the latter by suitable connections G to the receiving set E,

which is placed wherever desired within the building. While only one station is shown herein, it will be understood that others similar thereto will be provided, although this is not essential since my receiver and my transmitter can be made to operate with others of different design.

The transmitting circuit CAB is supplied with power and controlled through the ,power unit D which is situated for convenience at the operating'position near the receiving set E. The connection'between C and D is by a-metal sheathed or BX cable F having a round connection H containin a switch to enable groundin the sheathing at the time of installation it desirabler Inside the metal sheathing F are the three wires connecting C and D, while between D and E four wires are used.

loo 7 In the specific embodiment shown herein vacuum tubes are employed, but it is to be understood that the circuit CAB may be any. well-known power oscillating circuit used for transmitting, the oscillator being located in C. fWhere vacuum tubes are used the power unit D may include storage battcries to heat the transmitting and receiving tube filaments and to run a dynamotor which furnishes higher voltage power to the transmitter and modulator tubes. The receiving circuit may also be any one of the wellkuown circuits. The circuit CAB has no operating adjustments, except for wave-length,

which is seldom altered, the control of the station for either telephony or telegraphy being from the position of E.

Referring to Figure 2, 1 and 2 are inductances coupling the grid and plate circuits of the transmitting oscillator 5, pro ducing oscillations in the resonant circuit A13 3 is a grid' leak and condenser to maintain the grid at proper value of negative potential from the filament so as to 0btain maximum tube eflicicncy, while 4 is a condenser to pass radio frequency but preventing the high voltage between the plate and the filament from short-circuiting through coil 1. 6 are radio frequency chokes to prevent transinitterradio frequency current from leaving or going below C, thus localizing all transmitter radio frequency at CAB. By grounding the metallic sheathing F it will now'be seen that any leak of transmitter radio frequency beyond chokes 6 passes to ground through switch I and wire H by reason of the capacity between the conductors inside the sheathing F and the sheathing itself. Two of these conductors carry the heating current for the filament, and one of these and the third supply high voltage power from the d-ynamotor 8 between the filament and plate of oscillator, 5. The power unit D may consist of a box with parts arranged for compactness and convenience in charging, adjustment, etc,

and contains storage battery 12 to heat the filament of power oscillator-.5, the filament of power modulator 9, and runs the dynamotor 8. 11 is a sending telegraphirelay controlled from E, and it will be seen that when relay 11 is closed the negative pole of the high voltage source 8 is connected to the filaments of tubes 5 and 9, while the positive ole of the high voltage source is connected first through the voice-frequency choke coil 7 and then to the plates of tubes 5 and 9.

' The choke 7' causes the total current to both tubes to be constant .at voice frequency, so

that if the current in modulator 9' is sud denly decreased the current in oscillator 5 is increased, and vice Versa. The tub-e 9 is voice controlled by a telephone transmitter 16 connected iniseries with a battery 14 and the primary of modulation transformer 10,

the secondary being connected between the grld and the filament of the power modulator. The battery 14 heats the filaments of detector tube 19 and amplifier tube 20 lo-- catcd in E, and also supplies current for telephone transmitter 16, the telegraph relay l1, and break-in and key click eliminator relay 17.

Reception is by loop 18, detector tube 19, and audio frequency amplifier 'tube 20. 23 is an audio frequency transformer adapting the plate or output circuit of detector 19 to the grid or input circuit of the amplifier 20. Condenser 25 is provided to pass only radio frequency current around the relatively high impedance primary of transformer 23: The

non-magnetic. Since the telephone receivers 27 are in series with contacts 30, 31 and secondary ofkey click eliminator transformer 24, reception is only possible when key 28 is closed. Transmission of telegraphic signals is by key 28, which closes contacts 29 and 30, in series with storage battery 14 and the coil of signal relay 11, the contacts of the latter making and breaking the negative lead from the high voltage power supply. Transmission as well as reception is possible only when key 28 is closed, or its side lever closed. where the operator does not desire to manually hold the key down, thus affording break-in telegraphy. By this is meant a duplex system of telegraphic communication wherein during the communication both the sending and the receiving keys Y are closed, thereby producing a beat note at each station only when both keys are closed,

and the opening of either key destroying the signal beat note'at both stations, assuming that the local receiver and incoming oscillations are so tuned as to produce a beat note. With the receiving set tuned to the incoming signal, a sending operator bears his own sending just as a wire operator using a sounder does. and opening of the key by the receiving operator destroys the beat note at both stations to effect a break.

By providing transformer 24, and connecting receivers 27 across the secondary of transformer 24 with contacts 30, 31 in series, key click is eliminated, as would not be the case if the receivers were directly in series with plate battery 26, because they would then carrydirect current from battery 26 and passes the audio frequency signalcurrent,

thus entirely removing key click. from this source. Another source of key click would be the use of a simple relay in place of the specialkey click eliminator relay 17, since an'ordinary relay upon an opening would produce a key click due to the make and break of the high' voltage contacts. By the use of the third contact. and the arrangement for opening and closing the contacts 29, 30, 31 successively, click from this source is eliminated, because the telephone receivers are disconnected from the circuit at the instant of either making or breaking the high voltage supply at signal relay 11. The direct current passing through key 28 is kept as low as possible, and suitable condensers are shunted across the key 28 and signal contacts at 11.

While relay armature of 17 is herein shown as actuated by the coil controlled by key 28, it is to be understood that I'do not restrict myself to such arrangement, as it is obvious that-29, 30, 31 can be directly manually actuated with the elimination of key28 and the relay coil, if desired.

For telephoning, the key 28 at each station is closed.

In the system as above described local paralysis is eliminated, thus permitting both the sending and receiving sets to be in the same building, one being above the other, and

also to operate with very high efficiencies.

The use of a closed loop for receiving and an open antenna for transmitting permits the. receiving and sending elements to be brought. nearer each other because of the reduction in 'both electrostatic and magnetic coupling between 'the two elements! It is found in the arrangement of Figures 1 .and 2, wherein a counterpoise is used in connection with an elevated aerial for sending and a loop for receivingbelow the counterpoise that the effect of magneticcoupling is negligible at the powers now in use and that making the effect of accidental capacity coupling to the loop zero obviates local paralysis. I prefer the use of a small loop and to increase the receiving sensitiveness to the desired value by one or possibly more stages of audio frequency amplification. Radio frequency amplifiers are not desirable as they would tend to increase any accidental transmitter radio frequency in the loop circuit and thus cause local paralysis. By using a counterpoise, the parts carrying transmitter radio frequency are between the aerial and the counterpoise at C, thus localizing the entire transmitting circuit so that it can be installed on the roof of a building. With this done it is found that the receiving loopset, with entire set with power.

circuit design. It is found desir ness to the antenna, although in the. same building belowthe counterpoise, is operatively free from local paralysis, thus bringing the transmitting and receiving circuits physically closer to each other than has here tofore been considered possible but still electrically isolated from each other.

The choke coils 6 are important in assisting in the isolation of transmitter radio frequency current at C, but any leakage past these chokes is grounded by reason of the large capacity between the cables and the metal sheathing. The use of the sheathing also permits placing the receiving/loop near F, if desired, on account of space limitations. It will be understood that the grounding of sheathing F is precautionary, as this is unnecessary if the chokes6 function completely; in fact, under some circumstances, it is even found undesirable to ground it. For the metallic sheathing F could be substituted a condenser from each of the conductors to the ground, but this would not give the shielding effect of the armor such as F necessary to permit the receiving loop to be brought near the cables, whereas with F the receiving loop 18 can be as near as is desired.

It will be understood that the storage batteries, dynamotors, etc., could be replaced by a single generator designed to furnish the The storage batteries are placed together in I) to facilitate charging, andthe discharge rate from both batteries12 and 14 is made equal by proper a le to eliminate low frequency. inductioh noises from the dynamotor by enclosing it in a me-- tallic casing. For removing commutator ripple from the dynamotor suitable means are now known.

In installation, capacity coupling between the receiving loop and transmitter via ground, such as gas and water pipe, etc., must be reduced to a minimum, either by keeping the loop a suflicient distance from such objects or else by so designing the loop oscillating circuit that the capacity effect to ground is equal from both terminals of the loop, thus preventing transmitter radio frequency coming in via ground to the loop, thence entering the detector tube circuit and causing local paralysis. As herein shown, this object is accomplished by the adjustment of condenser 33' at the time of installa tion,together with the proper polarity of loop terminals 32. In using the receiving circuit in Figure 2 with condenser\33, if a grounded metallic object is closer to one side of the loop than the other and there is some local paralysis in the receiving set by a capacity coupling between the said object and the loop, reversing the loop terminals at 32 with condenser 33 disconnected will either Ian be of particular assistance.

said object or by leakage along the conduc tors joining O, D and E.

. Choke coils may also be inserted in the conductors joining D and E, at say position 15, to supplement the chokes at (i in C. It has been found that when F is not grounded. and poor chokes are employed at (3, there is leakage of transmitter radio frequency current to D, and thence by capacity coupling between the sending and receiving apparatus over D, and finally to the loop receiving circuit. In such acase would the chokes at 15 Chokes might also be inserted in the four wires, as indicated at 34, for the sanie purpose, but in present instruments chokes at 15 and 34 have not been found necessary.

To tell if the radio frequency receiving loop circuit is free from local paralysis, for given combination of transmitter and receiver wave-lengths, stop the transmitter from radiating and adjust the loop circuit toan oscillating state, and find some point to touch with a wet fingerwhich will give a click in the head receivers. -Then adjust the receiving circuit so as 'not to oscillate; no click will then be heard. Now if the transmitter is permitted to radiate again,

and no click is heard while touching the loop with finger as before, the receiving circuit 1s free of local paralysis for all practical purposes, whereas if a click is now heard the receiver is being affected (forced to oscillate) by the transmitter, either by transmitter radio frequency current leaking through improperly choked connecting conductors, or by electrostatic or magnetic induction. A much simpler way to tell whether or not there is local paralysis for aparticular combination of sending and receiving avelengths, etc., at each station, and the method used in making installations, is to set sender and receiver to desired wave-lengths and listen to the distant stations signal with and without the local sender radiating. If there is no difference in the intensity or quality of the incoming signal when sender is radiatingand when it is not then for all practical purposes the receiver is free of local paralysis. It is thought that electrostatic induction to the receiving loop has nearly alwayspredominated over magnetic coupling to cause local paralysis, except where the transmitter capacity is between aerial and ground (instead of between aerial and counterpoise), and the receiving loop is placed off to one side instead of underneath, as may be preferable for high power transmitters.

If the loop is two or three floors below the aerial-counterpois'e systen1, tl1ere does not seem to be any magnetic coupling whatever, even when the transmitter power is increased considerably. What coupling there v is from the transmitter causing local paralysis can invariably be eliminated by obtaining the right value of condenser '33 and polarity of loop 32 in Figure 2. If it is desired to operate the receiver and trans mitter at a station on substantially the same wave-lcngtlnsay almost near enough to produce an audible beat note, if the receiving set is oscillating, it may be found necessary to also position the receiving loop 18 relatively to the rest of the apparatus. This is especially true if large tran-sn'iitter power or a large receiving loop is utilized. These three installation adjustments also provide excellent means of adjusting the intensity of side tone at the time of installation.

In this system an efficienttransmitting circuit is localized between antenna and counter-poise on a roof; then below and in the same building receiving is confined to an efficient loop circuit. The arrangement of 32 and 33 in Figure 2 at the receiving loop,

therefore, simply balances the overflow, or

what transmitter radio frequency current may accidentally get away from the transmitter and be induced in the receiving circuit as by capacity coupling via gas and water pipes, etc. It is interesting to note that if condenser Figure 2, is large enough, it is the equivalent of grounding the filament of the receiving set, which is desirable in that it protects the receiver local frequency from changes due to operator touching exposed parts of the circuit having filament potential.

By radio frequency chokes, as at 6, Figure 2, is meant any unit or combination which might be connected to or inserted at a point to prevent radio frequency current from passing.

The receiver will be preferably operated. on a slightly different wave-length than the transn'iitter, because in telegraphy the beat note caused by the local transmitter would 'jam the distant signal, and for telephony there would be too loud a sidetone, or possibly howling such as occurs in wire telephones when receiver and transmitter are brought together. In telephony, the receiver will preferably be adjusted not to oscillate, but tickled up by feed-back 29.. For telegraphy, the effect of 22 will be made such asoto make receiving loop oscillate in the usual manner for continuous wave reception.

lVhat I claim is:

1. In a, radio communication system, a station comprising an elevated radiating element including an aerial and a counterpoise the ratio of whose effective capacity to inllll) llu ' operating with said aerial and forming.

ductance is relatively high, a receiving element below the radiating element whose ratio of effective capacity to inductance is relatively low, means for supplying power, and sending and receiving means.

2. In a station for simultaneous duplex radio communication, a radiating system having relatively high capacity and low inductance and a separated receiving system in the same building having low capacity and high inductance operating on different frequencies, means for shielding said receiving system from the field of said radiating system, and means for selectively operating the radiating system to transmit telegraphically or telephonically.

3. In a radio communication system, a station comprising an elevated radiating element, a counterpoise below the radiating element, a receiving element below the coun terpoise, and sending and receiving means.

.4. In a radio communication system, a station comprising an elevated radiating element, a counterpoise below the radiating element, a loop receiving element below the counterpoise, and sending and receiving means.

5. In a radio communication. system, a

station comprising an elevated radiating element, a counterpoise below the radiating element, means for supplying power to the radiating element, means for localizing sending radio frequency in the radiating element counterpoise circuit, a. receiving element below the counterpoise, sending means controlling the radiated power and receiving means controlling the received power, both located adjacent the receiving element.

6. A radio communication system including a radiating aerial, a counterpoise cotherewith a radiating system, a sending means connected to. said radiating aerial and counterpoise, and a receiving means having its receiving aerial located near the radiating system and in the zone shielded by the counterpoise.

7. A radio system arranged for duplex communication including a radiating aerial, a counterpoise cooperating with said aerial and forming therewith a radiating system, a sending means connected to said radiating aerial and counterpoise, a receiving means having its receiving aerial located near the radiating system and in the zone shieldedby the counterpoise, a source of power for the sending and receiving means, and means for preventing the transfer of radio frequency energy from the sending means to the source of power.

.8. A radio communication system including a radiating element having sending means cooperating therewith, a receiving loop having receiving means cooperating therewith, a single source of power for said sending and receivin means, and means for equalizing the capacity eifectto ground in the 'loop oscillating circuit, including a grounded condenser connected to one of the loop terminals whereby to prevent local paralysis in the receiving means by capacity coupling between the loop and adjacent metallic objects. a

9. A radio communication system embodying an elevated antenna and counterpoise, an elevated oscillating element adjacent the antenna and counterpoise, a receiving sta tion comprising a loop and an oscillatable element at such distance from the counterpoise as to be substantially out of the send ing field, sending and receiving controlling means adjacent each other and the loop, a power unit conveniently near the receiving station and connected to both the receiving loop and the sending oscillator, and means for preventing local paralysis of the receiving system. p

10. A radio communication system embody ing an elevated antenna and counterpoise, an elevated oscillating element adjacent the antenna and counterpoise, a receiving station comprising a loop and an oscillatable element at such distance from the counterpoise as to be substantially out of the sending field, sending and receiving controlling means adjacent each other and the loop, a power unit conveniently near the receiving station and connected to both the receiving loop and the sending oscillator, and means including sheathing for the power conductors between the power unit and the sending oscillator and chokes in the power conductors adjacent the sending oscillator, for preventing local paralysis of the receiving system.

11. In a station for duplex radio communication, a transmitting radiating element, signaling means controlling the radiations thereof, a receiving loop having one side connected to detecting means, detecting means located adjacent said signaling means, and a condenser between the other side of the loop and ground propor tioned to eliminate electrostatic coupling in the loop circuit due to objects within the field of said radiating element.

12. In a station for duplex radio communication, an open antenna radiating structure supported on a building, aunit for supplying oscillations thereto whose power supply and control come via metal covered conductors from within the building, a loop receiving set situated within said building and receiving on a different frequency from that of the transmitter, means for preventing transmitter energy from passing through said conductors to the receiving circuit, and

means for preventing transmitter energy.

from passing to the receiving circuit by electrostatic coupling with objects within the field of said antenna. 7

13. In a two-way radio communication system, an aerial and a counterpoise supan oscillat-v whereby to secure a proper balance of the I loop circui 15. In a duplex radio communicating system having a transmitting circuit operatively connected to a radiating antenna and a counterpoise, a receiving circuit operatively connected to a loop antenna, and a common source of power supply operatively cnnected to both of said circuits, a method of operating said system without paralyzing the receiving circuit by local transmitter energy which consists in preventing the transmission of radiated energy from the transmitting circuitto said receiving circuit, andbalancing out radiated energy in said loop caused by electrostatic coupling with adjacent metallic objects.

16. A duplex radio communication system comprising a power oscillating circuit including an aerial, a counterpoise and an oscillator, the oscillator being enclosed in aweatherproof box; a receiving circuit including a coil aerial, and detecting and ampllfying means, said means being enclosed 111 a metalllcshield; a power unit including means for supplying electrical energy to the oscillating and receiving circuits, said unit being enclosed in a metallic shield, and conductors connecting the power unit with the respective circuits, ductors being enclosed in grounded metallic shields.

17. In a simultaneous duplex continuous wave radio telegraph system having cut-in, controlled by a transmitting key, heterodyne reception through telephones, a transformer between the audio frequency circuit and the telephones, the latter being in the transformer secondary circuit, and switching means comprising successively operated contacts controlled by the key for eliminating key click in the telephones.

18. A two-way radio telegraph system comprising at each of two stations a sending antenna and a receiving loop, and a key with means whereby a local signal beat note is audible at each station when both keys are closed, means whereby opening of a key at one station effects a variation of the slgnal beat notes to effect a cut-in, and means controlled by the cutting in key to eliminate the beat note receivers.

19. In a station for duplex-radio communication, a transmitting radiating element and a vacuum-tube oscillating circuit connected thereto, the saidoscillating circuit receiving its filament and plate power supply from a distant generator, means for removing generator ripple in the plate power supply, a receiving system comprising a closed loop receiving element having detecting and amplifying means connected thereto, means for selectively operating the oscillating circuit to transmit telegraphic or telephonic radiations, and control means for the receiving circuit actuated by said operating means.

' Signed at New key click in York city, in the county of New York and State of New York, this third day of September, A. D. 1920.

PAUL WARE.

at least some of said conwith a; 

